1. Technical Field
The present invention relates to a lighting device, a liquid crystal display device, and an electronic apparatus.
2. Related Art
In recent years, liquid crystal display devices, such as liquid crystal panels, are widely installed in the image display units of various electronic apparatuses. For example, such liquid crystal display devices are suitably used in the display units of mobile devices such as mobile phones due to their slimness, low weight and low power consumption. The liquid crystal display devices mainly include a liquid crystal panel in which a liquid crystal layer is interposed between a pair of substrates, and a lighting device (backlight) disposed on the non-viewing screen side of the liquid crystal panel. Further, the orientation state of liquid crystal molecules is controlled by applying an electric field to the liquid crystal layer by transparent electrodes formed at the sides of the liquid crystal layer interposed between the pair of substrates, so that the incident light from the lighting device is modulated, thereby displaying an image.
The above-mentioned lighting device is mainly composed of a rectangular optical waveguide made of a light-transmissive material and a light source, such as a light-emitting diode (LED), which is disposed adjacent to the optical waveguide. The optical waveguide is formed with patterns of grooves or protrusions. Further, the light emitted from the light source and which is also incident from the side of the optical waveguide is reflected from the grooves or protrusions to be emitted from the main plane of the optical waveguide toward the liquid crystal panel. Japanese Unexamined Patent Application Publication Nos. 2001-133776 and 2001-184923 are examples of the related art.
However, because the above-mentioned mobile devices are widely used in public places, many mobile device users are frequently concerned about revealing their personal information, etc. to others while using it. On the other hand, because the liquid crystal display devices generally have a narrow viewing angle, it is difficult to read the display from a direction deviating from the viewing angle. Therefore, liquid crystal display devices have a usability problem.